Storage stable, one package, heat curable polyurea/urethane coating compositions and method of preparation

Abstract

New and improved storage stable, one package, heat-curable polyurea/urethane coating compositions are disclosed which comprise: (a) a mixture or prepolymer of (i) a poly aliphatic isocyanate compound of the formula: ##STR1## wherein R and R' are each, independently, hydrogen, alkyl or substituted alkyl and X is a bridging means selected from divalent aliphatic, cycloaliphatic, or aromatic groups, or a polymeric adduct of said aliphatic isocyanate compound possessing poly aliphatic isocyanate functionality; and (ii) an approximately stoichiometric amount of at least one monomeric or polymeric compound containing a plurality of isocyanate reactive hydrogens; and (b) a minor effective amount of a polymerization catalyst. The compositions cure when heated to above about 100° C. to form coatings which exhibit good abrasion resistance, solvent resistance, weather resistance and good adhesion to a wide variety of substrates. The coating compositions are stable upon storage for several months and have useful coating lives in the presence of atmospheric moisture of up to several days.

What is claimed is: 
     
       1. A one package, storage stable heat-curable poly urea/urethane coating composition, said composition comprising: (a) a mixture or a prepolymer of (i) a poly aliphatic isocyanate compound of the formula: ##STR7##  wherein R and R' are each, independently, selected from hydrogen, alkyl or substituted alkyl and X is a bridging means selected from divalent aliphatic, cycloaliphatic or aromatic groups, or a polymeric adduct of said aliphatic isocyanate said polymeric adduct possessing polyaliphatic isocyanate functionality; and   (ii) at least one monomeric or polymeric compound containing a plurality of isocyanate-reactive hydrogens, wherein the molar ratio of the total isocyanate groups in (i) to the total reactive hydrogens in (ii) is from about 1:0.8 to about 1:1.2, respectively; and     (b) a minor effective amount of a polymerization catalyst.   
     
     
       2. A poly urea/urethane coating composition as defined in claim 1, wherein component (a) (i) comprises α,α,α',α'-tetramethylxylylene diisocyanate. 
     
     
       3. A poly urea/urethane coating composition as defined in claim 1, wherein component (a) (i) comprises a polymeric adduct of a poly aliphatic isocyanate compound and a hydroxyl terminated polyether, said adduct having aliphatic isocyanate terminal groups. 
     
     
       4. A poly urea/urethane coating composition as defined in claim 1 wherein component (a) (i) comprises a polymeric adduct of a poly aliphatic isocyanate compound and a hydroxyl-terminated polyester, said adduct having aliphatic isocyanate terminal groups. 
     
     
       5. A poly urea/urethane coating composition as defined in claim 1, wherein component (a) (ii) comprises a polyol compound. 
     
     
       6. A poly urea/urethane coating composition as defined in claim 1, wherein component (a) (ii) comprises an aminoalcohol or a polyglycolamine. 
     
     
       7. A poly urea/urethane coating composition as defined in claim 6, wherein the aminoalcohol or polyglycolamine is added in an amount sufficient to provide about one equivalent of amino groups for each equivalent of isocyanate groups. 
     
     
       8. A poly urea/urethane coating composition as defined in claim 1, wherein component (a) (ii) comprises 9-amino-10-hydroxystearylamine. 
     
     
       9. A poly urea/urethane coating composition as recited in claim 1, wherein polymerization catalyst component (b) comprises dibutyltin dilaurate. 
     
     
       10. A one package, storage stable heat-curable poly urea/urethane coating composition, said composition comprising: (a) a solution of a prepolymer of α,α,α',α'-tetramethylxylylene diisocyanate and 9-amino-10-hydroxystearylamine in N,N-dimethylformamide, said solution containing from about 30% to about 80% by weight solids content and having an isocyanate content of from about 2% to about 10% by weight, based upon the total weight of the solution wherein the molar ratio of the total isocyanate groups in (a) (i) as recited in claim 1 to the total reactive hydrogens in (a) (ii) as recited in claim 1 is from about 1:0.8 to about 1:1.2, respectively; and   (b) from about 0.001 to about 10.0 parts by weight of dibutyltin dilaurate, per 100 parts by weight of (a).   
     
     
       11. A method for preparing a one package, storage stable, heat-curable poly urea/urethane coating composition, said method comprising: (a) forming a liquid mixture of a poly aliphatic isocyanate compound of the formula: ##STR8##  wherein R and R' are each, independently, selected from hydrogen, alkyl and substituted alkyl and X is a bridging means selected from divalent aliphatic, cyclo-aliphatic or aromatic groups, or a polymeric adduct of said aliphatic isocyanate compound possessing poly aliphatic isocyanate functionality in a suitable solvent;   (b) cooling liquid mixture (a) to a temperature of from about 0° C. to about 10° C.;   (c) forming a liquid mixture of at least one monomeric or polymeric compound containing a plurality of isocyanate-reactive hydrogens in a suitable solvent;   (d) adding the mixture of step (c) to the cooled mixture of step (b) to form a reaction mixture;   (e) permitting the reaction mixture of step (d) to come to room temperature and allowing the reaction to continue at room temperature for a time sufficient to provide a prepolymer solution containing about 30% to about 80% by weight solids; and   (f) thereafter, adding to said prepolymer solution formed in step (e), a minor effective amount of a polymerization catalyst to provide a storage stable, one package, heat-curable poly urea/urethane coating composition.